I second the opinions of others that JavaFX is too closed which, I think, hinders the work of library and app developers.
I wonder if the reasons that were used to make this design decision back when JavaFX was being created still hold true. Back in the beginning there were more developers involved in developing JavaFX, significant features were added at a fast pace so the fact that it was closed wasn't such a big drawback as things were changing quickly and missing features that were spotted could be added relatively quick. Commenting more specifically on your question... I think Skins could benefit generally from being easier to extend. The promise of skins is that you could easily replace a control behavior and visuals without changing its model (the model being the part of the control that developers usually interact with) but the problem is that the JavaFX SDK control's skins are very difficult to extend. Say, if you only want to add a specific visual feature (something that CSS can't do) it takes a significant effort. What you usually see is that developers opt to create completely new controls rather than just new skins. My attempt at providing new skins for existing javafx sdk controls is here: https://github.com/dukke/FXSkins Still it required quite a bit of effort.. at least more than it could ideally take (I think). The advantage of this kind of approach (providing new Skins) and the library I created "FXSkins" is that you can enhance the controls of your existing app very easily by setting new skins in the CSS stylesheet. You won't need to change anything directly in the code. Regarding the current state of the JavaFX SDK Skins, there isn't a clear MVC separation, the skin does the Controller and View part at the same time. Perhaps ideally there would be a clear View part that could easily be extended to add different advanced visuals to the control (by advanced I mean, anything that can't be done with CSS). And then perhaps also the Behavior part where you can easily change the control's functionality. I remember at some point Richard Bair saying that it was a goal to make Behaviors public. Thanks! -- Pedro Duque Vieira - https://www.pixelduke.com
